This invention concerns changing of the service profile of a mobile station subscriber in a public land mobile network, wherein the subscriber may move freely from one location area to another and wherein there are functions to determine the subscriber""s location with at least location area precision.
Referring to FIG. 1, the following is a brief description of the structure and operation of a public land mobile network (PLMN). The names of network elements are the same as in the known GSM mobile network. Other digital mobile networks include the same network elements as those used in the GSM network. Communication between a mobile station (MS) in a cell and the network takes place via the radio path by way of a base transceiver station (BTS). Base transceiver stations BTS are connected to a base station controller (BSC). One base station controller BSC usually controls several base transceiver stations BTS, which may be chained to one another or cabled directly to the base station controller, as is illustrated in the FIGURE. The geographical area covered by these base transceiver stations is called location area (LA). Each location area has its own unambiguous location area identity (LAI), and the traffic of mobile stations located within the area goes through the base transceiver stations of the area and through the base station controller controlling the location area. FIG. 1 shows three location areas. The mobile station may move in the location area without any need to update the location information concerning itself.
Several base station controllers are connected to one mobile switching centre (MSC). The entity of location areas under the mobile switching center""s control is called the mobile services switching centre area. If the public land mobile network includes several mobile switching centers, then their switching center areas together form a PLMN area, which means the geographical area covered by one network. The network is run by one operator almost in all cases.
The public land mobile network also includes various databases.
In the home location register (HLR), of which there may be several, the in formation on subscribers is stored permanently irrespectively of the current location of the subscriber. The visitor location register (VLR) is nowadays integrated with the mobile switching centre, and it stores subscriber information fetched from a home location register while the subscriber visits the VLR""s area, that is, the mobile services switching centre area. For example, in FIG. 1, subscriber information relating to mobile station MS located in location area LA is stored in visitor location register VLR located in connection with mobile switching centre MSC.
Location update is always done when the subscriber connects to the network and always when the subscriber moves from one location area to another. Location update may also be done periodically at certain intervals. This is called periodic location update. After the location update the HLR knows the address of that VLR in the relating switching centre area of which the subscriber is located, and the VLR knows the identity of that location area in which the mobile station is located. When the subscriber is moving anywhere in the network, this information will be updated.
Reference is still made to FIG. 1 and also to FIGS. 2A-2C. FIG. 1 is a brief illustration of that numbering information which is essential to the invention and which the different network elements have, as well as the numbers stored on the subscriber identity module of the terminal equipment. FIGS. 2A-2C show the contents of numbers.
FIG. 2A shows the content of the location area identity. The identity is formed by the mobile country code (MCC), for Finland that code is 244, by the mobile network code (MNC), in Finland 91, and by the location area code (LAC). Thus, the operator""s location area identities differ from each other only as regards the LAC code. Location area identity LAI is in the memory of base station controller BSC of this area. When the mobile station is in some location area, it has also received location area identity LAI of this location area from the network and it has stored it in its own memory.
The mobile station""s SIM module stores the mobile station""s connection number (telephone directory number) MSISDN, the contents of which are in accordance with FIG. 2B. It is formed by the country code (CC), which is 358 for Finland, by the national destination code (NDC), which for the operator xe2x80x9cSoneraxe2x80x9d in Finland is 40 or 400 and by the subscriber number (SN). What is essential is that a mobile station subscriber may have several MSISDN numbers, because in actual fact the number defines the service used and not the telephone equipment itself.
FIG. 2C shows an IMSI (International Mobile Subscriber Identity) which is a special subscriber identity number, which is used both for identifying the subscriber and for security purposes. When doing a location update and always when asking for a channel from the network, the mobile station will send its IMSI number to the network, and only after the network and the mobile station have agreed on encryption of the radio link the mobile station will send its MSISDN number encrypted to the network. When doing a location update, the mobile switching centre/visitor location register use IMSI number when asking for subscriber information from the home location register. What is essential is that the subscriber in most cases has only one IMSI number, although there may be several MSISDN numbers. Home location register HLR is the place where these numbers are tied to each other.
Based on the description referring to FIGS. 1 and 2A-2C, home location register HLR always stores the subscriber""s connection number/numbers MSISDN, the subscriber""s international mobile subscriber identity IMSI and the address of that visitor location register VLR, where the subscriber is located. Besides the subscriber""s MSISDN number and IMSI number, the visitor location register also stores location area identity LAI and thus also the location area code of that location area where the subscriber is located at the moment. Mobile station MS stores the MSISDN and IMSI numbers and location area identity LAI. In addition, the mobile station stores the subscriber""s encryption parameters. When the MS is moving from location area a to location area b in FIG. 1, only the LAC code will chan memories of the mobile station and the base station controller and in the visitor location register. No changes take place in the home location register.
In digital PLMN systems traffic on the radio path is encrypted. For this purpose, an authentication and encryption procedure is performed in the beginning of the call setup using different algorithms and encryption keys. The simplified events in the GSM system are such that the mobile station sends its IMSI identity (or its temporary TMSI identity) to the network. Before traffic starts, authentication is performed by using a special identification algorithm stored in the mobile station as well as subscriber-specific identification key Ki. In the early part of the authentication, the network sends a random number to the mobile station. Using this and subscriber-specific key Ki in the module the mobile station carries out an identification algorithm. The mobile station uses the received random number and the Ki value also for calculating connection-specific encryption key Kc. In this calculation another algorithm is used which is stored in the subscriber identity module. This encryption key is used as a key to a third algorithm which is stored in the subscriber identity module and which is then used for encrypting speech and data transmission over the radio path. With the same values the network performs the same algorithms and thus obtains the same encryption key as the result. Both store the key in their memory.
The mobile station always sends the MSISDN number encrypted. When the mobile switching centre has received the number, it may inquire from the home location register to learn what kind of services relate to this MSIDN number.
In actual fact, mobile station MS is formed by two parts: by the mobile equipment (ME) and by the subscriber identity Module (SIM), so functioning mobile station MS is formed only by inserting the SIM module into mobile equipment ME. The above-mentioned MSISDN, IMSI, subscriber-specific key K, and the algorithms needed in authentication and encryption are all stored permanently on the subscriber identity module, which the subscriber receives from the operator when subscribing to the network. The algorithms are carried out on the SIM module, so that the Ki key need never be transferred between the SIM module and mobile equipment ME.
Mobile operators provide subscribers with a lot of different services. In the following some examples will be given as a list. The short message service is specified in the standard and using this the mobile subscriber may leave and receive messages of a certain length. Faxes may be sent and received in the fax answering service. In the availability service, calls are directed immediately forward to the number given by the subscriber, if the mobile subscriber can not be reached. Call forwarding differs from the availability service in that the subscriber himself and using his own mobile station states the number to which calls may be forwarded. In the answering service the call is directed to an answering machine, if not answered within a certain time, when the telephone is closed or outside the service area. The caller may dictate his message to the answering machine and the subscriber may listen to it when he likes. In the secretary service, the call is directed to a secretary, who receives the messages and tells the caller about any notifications given by the subscriber. In addition, various services relate to the pricing of a call, such as a) a detailed bill service, whereby the subscriber receives the duration and prices of made calls together with the bill, b) a payer specification, wherein by a code placed before the number of the called subscriber information can be given on whether the call is a business call or a private call. In addition, the mobile subscriber may order from the operator various services relating to a limitation of outgoing and incoming calls.
Some services are free of charge and some entail a charge. Since there are many services, the operator usually offers some basic services to the subscriber free of charge, but the subscriber has to order such services himself which entail a charge. The subscriber chooses the services he wants and the operator stores the information on which services the subscriber is entitled. to in the subscriber information of the home location register. The entity of these entitled services is called the service profile in this application. Thus, each subscriber has his own service profile. The service profile is tied to the subscriber connection, in practice to the MSISDN number.
It was said above that a subscriber may have several MSISDN numbers. In this connection several ways of using this feature have been presented. The U.S. Pat. No. 5,448,622, Huttunen, presents a mobile station, in the memory of which several telephone numbers are stored. They may be in use at the same time. Hereby, when a call comes, the call number is seen in the display, so the subscriber sees to which number the call is and he may answer it or not answer it. Through the operating connection the subscriber may activate a set of telephone numbers, where incoming calls are answered, and likewise through the operating connection the subscriber may choose which number is to be used in outgoing calls. Thus, the service profile is formed mainly by a chosen set of MSISDN numbers.
The U.S. Pat. No. 5,657,373, Hermansson et al, presents a system, where for each subscriber connection there are one subscriber number and at least two subscriber identity modules (SIM), which when inserted into the telephone will open the telephone for traffic. When there are two modules, one may be a full-sized module and the other a small size module, whereby both may be in the telephone at the same time. Opening of a subscriber connection takes place so that when one module is activated for incoming and outgoing calls, other modules are deactivated. Activating and deactivating of modules takes place in home location register HLR, whereby the subscriber must ask the operator to carry out the change work. Although there is only one subscriber number, each module has different IMSI, which is also stored in the subscriber information of the home location register. The home location register connects the subscriber number to that IMSI number in the subscriber information, which belongs to the module which is to be activated. Using the method presented in this patent it is possible in principle for each IMSI number to bring about a service profile of its own, whereby the subscriber would have several different service profiles. Hereby the subscriber would change his service profile by asking the operator to link up a MSISDN number with a desired IMSI number in the home location register. Thereupon he would insert the module having the said IMSI number into his mobile equipment.
U.S. Pat. No. 5,428,666, Fyfe, presents an arrangement by which a mobile station may use services of several different cellular systems. This happens in such a way that the mobile station has a memory containing several NAMs (Number Assignment Module). Each module contains data containing the number of the mobile station, the identity of that system whose services may be requested by using this telephone number and a certain set of control channel identities of this system. When the user wishes to use services of a certain system, he enables the module concerning this system, whereby the mobile station scans the control channels stated in the module and chooses the most powerful one of them. Thereupon the NAM system identity decoded from the chosen control channel is compared with the identity stored in the module, and when they are identical, access to the concerned system is granted. In this case the service profile could be formed so that the subscriber would agree with the different system operators on a profile in the concerned system and he would put the desired profile in use by activating the NAM module containing the identity of the system in question. The advantage is greatest the more the coverage of the systems is mutually overlapping.
There are some drawbacks in the changing of the service profile made possible by the prior art publications described above. In the solution according to Huttunen""s patent it is possible at least in theory to connect with each MSISDN number a service profile of its own. However, the user would have to choose the number he desires through the operating connection and, in addition, he would have to remember what kind of profile is connected with each number. According to the patent of Hermansson et al., several subscriber identity modules are required, and when use of a service profile relating to a certain subscriber identity module is required the operator must be asked to make the changes needed in the home location register. Making the change in the home location register takes its own time. When using the solution proposed by Fyfe, it is not possible at all to change the service profile when using the subscriber connection of the same operator.
It is a common feature of all that changing of the service profile does not take place automatically and that changing is slow. It should also be noticed that in a manual change of the service profile the dependence on the location is not taken into account at all, but the subscriber may choose any predetermined profile. Hereby the operator has no chance to influence the loading of the network by way of the service profile.
However, it is desirable in some situations even quite quickly to change even a big part of the services of a connection. From the operator""s viewpoint this would be especially advantageous if the profile could be tied to the mobile subscriber""s current location in the network. Hereby a profile would be available to the subscriber in a certain part of the network while another profile would be available to him in another part of the network. For example, fast data transmission could be made permissible for the subscriber in areas with a scarce population only, but not in city centres where there are not so many traffic channels available or where at least occasionally there occurs a shortage of free channels.
An objective of the present invention is thus a system in which the mobile subscriber""s service profile changes automatically and depending on the place, in other words, a system allowing place dependence of services tied to a mobile station connection.
The established objective is achieved by the definitions presented in the independent claims.
The system includes three functional parts located in the mobile station: a location part, an evaluation part and the subscriber connection exchange part. In addition to these, the home location register contains individual subscriber connections with a different service profile.
The duty of the location part is to make clear the mobile station""s location in the network and to give the location information in a suitable form to the evaluation part. The location part preferably uses a feature already existing in known public land mobile networks, that is, that the mobile station receives such parameters from the network from which the location data may be deduced with a different precision. Such parameters relating to the location information are e.g. the country code, the operator identity, the switching centre identity, the cell identity, the location area identity etc. The location part gives one parameter to the evaluation part as location data, or alternatively it may give a set of parameters.
Alternatively, the location part may be implemented by using any known method of location a mobile station.
The evaluation logic part contains a memory. The memory may be a number assignment module NAM storing a desired quantity of location data in the same form as is given by the positioning part. To each location data relates connection data, which may be a MSISDN number, if the subscriber has several MSISDN numbers but only one IMSI number, or an IMSI number, if the subscriber has several IMSI numbers but only one MSISDN number. In addition, to each connection data relates data containing special conditions. Each piece of location data, connection data and special data may form one record which is stored in the NAM module.
When the evaluation logic receives location data from the location part, it checks if the location data has changed compared with the location data received earlier. If it has, it searches the memory for the corresponding location data and compares the connection data in the record with the current connection data. If the connection data is identical, the process will wait for new location data. If the connection data is different, the evaluation part deduces that the connection must be exchanged for a new one and that a connection change operation must be started. However, prior to this it checks the record to find out whether any special conditions relate to a change of connection. Desired limitations concerning the change of connection may be laid down in the special conditions. For example, a certain number of identical location data must be received, whereby a hysteresis is achieved as regards the change. It may also be a condition that the connection may not be changed while a call is going on. Only after the evaluation part has decided that the connection is to be changed, it will give a connection change command to the connection exchange part. The exchange command contains the MSISDN number of the new connection.
The connection exchange part begins the connection exchange operation in response to the received command. This may take place in such a way that it disconnects the mobile station from the network and reconnects to the network using a new MSISDN number. The algorithms and encryption keys relating to this number it fetches from the memory, which may be common with the evaluation logic part. The network searches the home location register for subscriber data relating to this MSISDN number and along with this also the service profile relating to this number. Authentication is performed in the normal manner, and after the registration the subscriber may begin traffic on the new connection and using the service profile relating to this connection.
All three functional parts in the mobile station: the location part, the evaluation part and the subscriber connection exchange part, are preferably implemented in the subscriber identity module SIM.